Time-resolved spectral investigations of laser light induced microplasma

✍ Scribed by L. Nánai; I. Hevesi

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 354 KB
• Volume: 48
• Category: Article
• ISSN: 1386-1425
• DOI: 10.1016/0584-8539(92)80193-z

✦ Synopsis

The dynamical and spectral properties of an optical breakdown microplasma created by pulses of different lasers on surfaces of insulators (KCI), metals (Cu) and semiconductors (V,O,), have been investigated. Experiments were carried out in air and vacuum using different wavelengths @=0.694pm, type OGM-20,1= 1.06pm with a home-made laser based on neodymium glass crystal, and 1. = 10.6pm, similarly home-made) and pulse durations (Q-switched and free-running regimes). To follow the integral, dynamical and spectral characteristics of the luminous spot of microplasma we have used fast cameras (SFR-2M, IMACON-HADLAND), a high speed spectral camera (AGAT-2) and a spectrograph (ST%1). It has been shown that the microplasma consists of two parts: fast front (peak) with r=lOO ns and slow front (tail) with ~1~s durations. The detonation front speed is of the order of =ldcms-' and follows the temporal dependence of p4. It depends on the composition of the surrounding gas and its pressure and could be connected with quick evaporation of the material investigated (peak) and optical breakdown of the ambient gaseous atmosphere (tail). From the delay in appearance of different characteristic spectral lines of the target material and its gaseous surrounding we have shown that the evolution of the microplasma involves evaporation and ionization of the atoms of the parent material followed by optical breakdown due to the incident and absorbed laser light, together with microplasma expansion.